;;-*-Lisp-*-
(in-package goal)

;; name: timer-h.gc
;; name in dgo: timer-h
;; dgos: ENGINE, GAME

#|@file
There are two sources for timing:
- EE TIMER1, used for the frame profiler. There are 9765 counts of this per frame. It gets reset in drawable.
- The "stopwatch" system, used for reading the CPU clock cycle counter, at 300 MHz (32-bit)
|#

;; The Emotion Engine has 4 hardware timers, timer1 is used as the
(defconstant TIMER0_BANK (the timer-bank #x10000000)) ;; has HOLD register!
(defconstant TIMER1_BANK (the timer-bank #x10000800)) ;; has HOLD register!
(defconstant TIMER2_BANK (the timer-bank #x10001000)) ;; does NOT have HOLD register!
(defconstant TIMER3_BANK (the timer-bank #x10001800)) ;; does NOT have HOLD register!

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; PC Port Timer
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defmacro get-cpu-clock ()
  "Read the 300 MHz clock."
  ;; __read-ee-timer is a 300 MHz timer from the C Kernel.
  ;; it's a real timer.
  `(the uint (logand #xffffffff (__read-ee-timer)))
  )

(defmacro get-bus-clock/256 ()
  "Read the 150 MHz / 256 clock."
  ;; 300 MHz / (2^9)
  `(the uint (logand #xffffffff (shr (__read-ee-timer) 9)))
  )

(#when PC_PORT
  ;; the bus clock can be reset, which just stores the current count here.
  (define *timer-reset-value* (the uint 0))
  )

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Timer HW
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; +++timer-clock-selection
(defenum timer-clock-selection
  :type uint8
  (busclk 0)
  (busclk/16 1)
  (busclk/256 2)
  (hblank 3)
  )
;; ---timer-clock-selection

;; DECOMP BEGINS

(deftype timer-mode (uint32)
  "This matches the Tn_MODE register structure of the ps2 EE timers.
   Only the lower 32 bits of these registers are usable, and the upper 16 hardwired to zero."
  ((clks  timer-clock-selection :offset 0 :size 2)
   (gate  uint8 :offset 2 :size 1) ;; gate function enable
   (gats  uint8 :offset 3 :size 1) ;; gate selection: 0 = hblank, 1 = vblank
   ;; gate mode:
   ;;  0: count while gate signal is low
   ;;  1: start when gate signal rises
   ;;  2: start when gate signal falls
   ;;  3: start when gate signal rises/falls
   (gatm  uint8 :offset 4 :size 2)
   (zret  uint8 :offset 6 :size 1) ;; zero return: clear counter when equal to reference value
   (cue   uint8 :offset 7 :size 1) ;; count-up enable
   (cmpe  uint8 :offset 8 :size 1) ;; compare-interrupt enable
   (ovfe  uint8 :offset 9 :size 1) ;; overflow-interrupt enable
   (equf  uint8 :offset 10 :size 1) ;; equal-flag
   (ovff  uint8 :offset 11 :size 1) ;; overflow-flag
   )
  )

(deftype timer-bank (structure)
  "This matches an EE timer (without a HOLD register, timers 2 and 3).
Each register is 128-bits wide, but only the lower 32-bits are usable, and the upper
16-bits of that are hardwired to zero."
  ((count  uint32)
   (mode   timer-mode  :offset  16)
   (comp   uint32      :offset  32)
   )
  )


(deftype timer-hold-bank (timer-bank)
  "This matches an EE timer (with a HOLD register, timers 0 and 1)."
  ((hold  uint32  :offset  48)
   )
  )


(deftype stopwatch (basic)
  "Stopwatches are used to measure CPU clock cycles.
They don't use the timer above, but instead the Count COP0 register,
which counts CPU clock cycles directly."
  ((prev-time-elapsed  time-frame)
   (start-time         time-frame)
   (begin-level        int32)
   )
  )


(define *ticks-per-frame* 9765)

(defun timer-init ((arg0 timer-bank) (arg1 timer-mode))
  "Initiate a timer, start counting at a rate of 1 every 256 bus clocks (BUSCLK: ~147.456MHz)."
  (set! (-> arg0 mode) arg1)
  (set! (-> arg0 count) (the-as uint 0))
  0
  )

(timer-init
  (the-as timer-bank #x10000800)
  (new 'static 'timer-mode :clks (timer-clock-selection busclk/256) :cue #x1)
  )

(deftype sce-cd-clock (structure)
  ((stat    uint8)
   (second  uint8)
   (minute  uint8)
   (hour    uint8)
   (pad     uint8)
   (day     uint8)
   (month   uint8)
   (year    uint8)
   )
  )


(defun bcd-conv ((arg0 uint))
  "Binary coded decimal to integer"
  (+ (* 10 (the-as int (/ (the-as int arg0) 16))) (logand arg0 15))
  )

(define *month-days*
  (new 'static 'array uint32 12 #x1f #x1c #x1f #x1e #x1f #x1e #x1f #x1f #x1e #x1f #x1e #x1f)
  )

(defun is-leap ((arg0 uint))
  (or (zero? (mod (the-as int arg0) 400)) (and (not (logtest? arg0 3)) (nonzero? (mod (the-as int arg0) 100))))
  )

(defun mdy-to-day ((arg0 int) (arg1 int) (arg2 uint))
  (if (is-leap arg2)
      (set! (-> *month-days* 1) (the-as uint 29))
      (set! (-> *month-days* 1) (the-as uint 28))
      )
  (let ((v1-2 (+ arg0 -1))
        (v0-1 (+ arg1 -1))
        )
    (dotimes (a0-4 v1-2)
      (+! v0-1 (-> (the-as (pointer int32) (&+ *month-days* (* a0-4 4)))))
      )
    v0-1
    )
  )

(defun rtclock-to-secs ((arg0 sce-cd-clock))
  (let ((s5-0 0)
        (s4-0 (bcd-conv (-> arg0 year)))
        )
    (if (< s4-0 2000)
        (+! s4-0 2000)
        )
    (dotimes (s3-0 (+ s4-0 -1970))
      (+! s5-0 (* #x15180 (mdy-to-day 12 32 (the-as uint (+ s3-0 1970)))))
      )
    (+ s5-0
       (* #x15180 (mdy-to-day (bcd-conv (-> arg0 month)) (bcd-conv (-> arg0 day)) (the-as uint s4-0)))
       (* 3600 (bcd-conv (-> arg0 hour)))
       (* 60 (bcd-conv (-> arg0 minute)))
       (bcd-conv (-> arg0 second))
       )
    )
  )